/*
 * src/test/examples/testlibpq2.c
 *
 *
 * testlibpq2.c
 *		Test of the asynchronous notification interface
 *
 * Start this program, then from psql in another window do
 *	 NOTIFY TBL2;
 * Repeat four times to get this program to exit.
 *
 * Or, if you want to get fancy, try this:
 * populate a database with the following commands
 * (provided in src/test/examples/testlibpq2.sql):
 *
 *	 CREATE TABLE TBL1 (i int4);
 *
 *	 CREATE TABLE TBL2 (i int4);
 *
 *	 CREATE RULE r1 AS ON INSERT TO TBL1 DO
 *	   (INSERT INTO TBL2 VALUES (new.i); NOTIFY TBL2);
 *
 * and do this four times:
 *
 *	 INSERT INTO TBL1 VALUES (10);
 */

#ifdef WIN32
#include <windows.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <sys/time.h>
#include <sys/types.h>
#include "libpq-fe.h"

static void exit_nicely(PGconn* conn)
{
    PQfinish(conn);
    exit(1);
}

int main(int argc, char** argv)
{
    const char* conninfo = NULL;
    PGconn* conn = NULL;
    PGresult* res = NULL;
    PGnotify* notify = NULL;
    int nnotifies;

    /*
     * If the user supplies a parameter on the command line, use it as the
     * conninfo string; otherwise default to setting dbname=postgres and using
     * environment variables or defaults for all other connection parameters.
     */
    if (argc > 1)
        conninfo = argv[1];
    else
        conninfo = "dbname = postgres";

    /* Make a connection to the database */
    conn = PQconnectdb(conninfo);

    /* Check to see that the backend connection was successfully made */
    if (PQstatus(conn) != CONNECTION_OK) {
        fprintf(stderr, "Connection to database failed: %s", PQerrorMessage(conn));
        exit_nicely(conn);
    }

    /*
     * Issue LISTEN command to enable notifications from the rule's NOTIFY.
     */
    res = PQexec(conn, "LISTEN TBL2");
    if (PQresultStatus(res) != PGRES_COMMAND_OK) {
        fprintf(stderr, "LISTEN command failed: %s", PQerrorMessage(conn));
        PQclear(res);
        exit_nicely(conn);
    }

    /*
     * should PQclear PGresult whenever it is no longer needed to avoid memory
     * leaks
     */
    PQclear(res);

    /* Quit after four notifies are received. */
    nnotifies = 0;
    while (nnotifies < 4) {
        /*
         * Sleep until something happens on the connection.  We use select(2)
         * to wait for input, but you could also use poll() or similar
         * facilities.
         */
        int sock;
        fd_set input_mask;

        sock = PQsocket(conn);

        if (sock < 0)
            break; /* shouldn't happen */

        FD_ZERO(&input_mask);
        FD_SET(sock, &input_mask);

        if (select(sock + 1, &input_mask, NULL, NULL, NULL) < 0) {
            fprintf(stderr, "select() failed: %s\n", strerror(errno));
            exit_nicely(conn);
        }

        /* Now check for input */
        PQconsumeInput(conn);
        while ((notify = PQnotifies(conn)) != NULL) {
            fprintf(stderr, "ASYNC NOTIFY of '%s' received from backend PID %d\n", notify->relname, notify->be_pid);
            PQfreemem(notify);
            nnotifies++;
        }
    }

    fprintf(stderr, "Done.\n");

    /* close the connection to the database and cleanup */
    PQfinish(conn);

    return 0;
}
